2008-08-30 09:19:12

by Matthias Urlichs

Subject: [Regression] sshd hangs on close

"top" sees multiple instances of:

6008 root 20 3184 D 0 0:00.06 flush_cpu sshd: root@pts/13

This is 2.6.27rc5, preemption and tickless turned on, on a 4-CPU machine.
(OK, two hyperthreaded ones :-P) strace() shows that this happens on the
last close of its /dev/ptmx file descriptor, which hangs.

I'll do a bisect early next week unless somebody else identifies a likely
suspect.

--
Matthias Urlichs

2008-08-30 20:25:15

by Rafael J. Wysocki

Subject: Re: [Regression] sshd hangs on close

[Adding CCs]

On Saturday, 30 of August 2008, Matthias Urlichs wrote:
> "top" sees multiple instances of:
>
> 6008 root 20 3184 D 0 0:00.06 flush_cpu sshd: root@pts/13
>
> This is 2.6.27rc5, preemption and tickless turned on, on a 4-CPU machine.
> (OK, two hyperthreaded ones :-P) strace() shows that this happens on the
> last close of its /dev/ptmx file descriptor, which hangs.
>
> I'll do a bisect early next week unless somebody else identifies a likely
> suspect.
>

2008-08-30 21:15:30

by Andrew Morton

Subject: Re: [Regression] sshd hangs on close

On Sat, 30 Aug 2008 22:28:57 +0200 "Rafael J. Wysocki" <[email protected]> wrote:

> [Adding CCs]
>
> On Saturday, 30 of August 2008, Matthias Urlichs wrote:
> > "top" sees multiple instances of:
> >
> > 6008 root 20 3184 D 0 0:00.06 flush_cpu sshd: root@pts/13
> >
> > This is 2.6.27rc5, preemption and tickless turned on, on a 4-CPU machine.
> > (OK, two hyperthreaded ones :-P) strace() shows that this happens on the
> > last close of its /dev/ptmx file descriptor, which hangs.
> >
> > I'll do a bisect early next week unless somebody else identifies a likely
> > suspect.
> >

Please do `echo w > /proc/sysrq-trigger', send the resulting trace.